Pneumatic-dispatch apparatus



June 22 1926.

J. J. STOETZEL PNEUMATIC DISPATCH APPARATUS Filed July 17, 1922 gum/14 607,

Patented June 22, 1926.

UNITED STATES PATENT OFFICE.

JOSEPH JOHN 'STOETZEL, OF CHICAGO, ILLINOIS, ASSIGNOR OF FORT? PER GENT TO ATLAS DEVICES COMPANY, INCL,

A CORPORATION OF NEW YORK.

PNEUMATIC-DISPATCH APPARATUS.

Application filed m 17, 1922. Serial Rb. 575,4a5.

This invention relates to pneumatic dispatch tube systems and more especially to a power saving device or valve for control- ,lingand regulating the flow of air through the tube lines of the system, both when the lines are unoccupied by carriers and when carriers are in transit through the lines.

The device will be described in connection with so-called open vacuum systems to which the invention is especially well adapted, although it is not limited in its application to this particular type of system.

In the open vacuum type of pneumatic dispatch system, selected for the purpose of illustrating the invention, it is common to provide valve mechanisms situated in the suction tube between the transit line and the suction drum, which are constructed and arranged to maintain normally a partial or .fractional flow of air through the line when unoccupied by carriers, and to operate autoinaticallyto increase the air flow or force propelling the carrier through the tube line upon insertion of the carrier in the bell mouth entrance of the line. Thus, when the lines of the system are empty, the duty which the exhaust pump is called upon to perform is simply that required to malntain a partial or fractional flow of air through the line, which, in ordinary practice entails maintaining a vacuum of only twenty-seven inches, and the load is consequently inconsiderable, resulting in a substantial saving of power. In addition to efl'ecting a saving in power equal to the difference between that required to maintain a small fractional flow of air through they lines and that which would be necessary to maintain continuously a full flow, devices have also been developed for regulating the flow of air through the inlet end of the tube line, orin other words, the

force propelling a carrier through a tube line while the carrier is in transit, as by reducing the air flow or carrier propelling force when the carrier travels along a descendin grade in a long line of tubing, or travels t rough a short line. I

The present invention has reference particularly to a power control and regulating device of the type last mentioned which, 111 addition to being constructed and arranged to operate normally to maintain a partlal flow of air through the tube lines of the system when unoccupied by carriers, also operates automatically to cut down the carr er veniently housed in an upon static pressure conditions in the tube line, as well as the rate of air flow or kinetic energy of the moving air cblumn in the line between the carrier and the suction drumas in one ty of prior device, the device of the present lnvention is constructed and arranged to be actuated alone by static conditions in the line.

The device includes a valve with associated means for actuating it, which are conappropriate casing of the globe valve type an positioned usually in the suction tube connectlng the transit line with the suction drum. The valve situated in the suction tube, controls the flow of air through the tube line and' means are provided 'for normally maintaining the valve in a position slightly off its seat to permit a partial or fractional flow of air through the line with no carriers in transit. The valve is provided by means, such as a spring, urging it to its seated position, or rather to its in the form of a diaphragm which, like the first diaphragm mentioned, is responsive to variations in the. pressure or suction in the line and, in accordance with one arrange ment also, to the atmosphere, to which a side oflthe diaphragm is exposed, toactuate the va ve. c

7 Where a pair of diaphragms is employed, as in the preferred arrangement, one to counterbalance or float the valve, and the other to exert a' force to actuate the valve, the arrangement is such that the actuating diaphra ,so to speak, responds to a decrease 0 pressure or increase of suction in the line, as when a carrier is inserted, to increase the opening of the valve beyond its normal amount of opening; and'to respond to anincrease' of pressure while a carrier is in transit to move the valve back to its normally slightly open position. Such an.

increase in pressure in the line, while a caror excessive speed of the carrier along, for instance, a down grade fllght in a long line I of tubing, or through a short line, when the justment thereby reducing the movement of the air column to a partial or fractional flow and decreasing the propelling force acting on the carrier. In this way not only is there a substantial saving in power effected by the reduction in air flow while a carrier is travelling along descending grades, during which no propelling force other than the action of gravity is needed to move thecarrier along, but also excessive speed or racing of the carrier with consequent injury to the buffer heads, tube lines and flaps or doors is 'prevented;

In the preferred construction, hereinafter described, the valve is urged to its normally restrictive open position, determined by'the setting of a. screw, by means of a spring, and a pair of diaphragms are employed as hereinbefore noted, one to exert a force to substantially balance the valve against the action of the spring, and the other to move the valve toward and away from its seat in accordance with pressure conditions in the line, the valve balancing the diaphragm being in direct communication on one side with the suctiontube, and on the other side enclosing, with the valve actuating diaphragm, an area or chamber which is also in communication with the suction tube, and

the valve actuating diaphragm on its other side being in communication with the atmosphere.

The invention in its preferred form is illustrated in the accompanying drawings, in

which-- 1 Fig. 1 is a diagrammatic view of a tube me,

Fig. 2 is a sectional view. of the power control and regulating device, showin the valve in its normally open position, an

Fig. 3 is a view similar to Fig. 2 showing an increased valve opening to permit a substantial flow of air through the tube line.

In accordance with common practice, a tube line ofthe pneumatic dispatch system consists of a' sending or outgoing tube 1 provided withian open bell mouth entrance 5, at one end, and a flap or door 6 at the other end which. is the out-station. as for instance a counter, 8, and a returntube '7 provided with a similar fla or'door 9 at its discharge 'end at thev centra station 10. The outgoing tube 4 and return tube 7"are provided with a connection 11 joining these two, and the flap or door 6 is normally closed, as well as the door 9, to provide a continuous transit line which is joined by a connection 12, similar to the connection 11, to a suction tube 13 connecting the transit line with a suction drum 14. Situated in the suction tube 13, interposed between the transit line and the suction drum, is the power control and regulating device 15, the details of construction of which are illustrated on an onlarged scale in Figs. 2 and 3.

Referring to these figures, the device includes a valve casing 16 in the form of a globe valve casing and a diaphragm casing 1.7 integral therewith, these casings enclosing the valve and its actuating mechanisms for controlling the flow of air through the line. The valve casing 16 has a port or opening 18 at right anglesto the suction tube for the passage of air from the portion of this tube above to that below the valve device, thence to the suction drum. The port or opening 18 is controlled by a valve 19. The

valve is threaded on a sleeve 20 which slides loosely on a connecting rod 21. The connecting rod 21 at one end reciprocates in a hearing plug 22, the latter being threaded into a cover plate 23 closing one side of the valve casing. The inner end of the plug 22 forms an abutment for the spring 35 the tension of which may be varied by adjustment of the plug. The opposite end of the connecting rod 21 is secured to the central portion 24 of a diaphragm 25 which has been referred to as the valve actuating diaphragm. Also slidably mounted on the connecting rod 21 is a short sleeve 26 which is secured to the central portion 27 of the diaphragm 28 which has been referred to as the valve balancing diaphragm. Passing through the connecting rod at a point between the'sleeve 20 and the sleeve 26 is a stop in the form of a pin 29. The diaghragms 25 and 28 are mounted within the iaphragm casing 17 provided with ports or openings 30 to the atmosphere. The diaphragm 25 divides ,the space within the diaphragm casing 17 into an area or chamber 17 common to both (liaphragms 25 and 28, and a chamber 17 on the outer side of the dia hragm 25 which is in communication wit the atmosphere. .The area or chamber 17 communicates with the upper portion of the suction tube 13 through a connection 31 having therein a passageway 32. the extent of opening of Wl'llCll is adjustable by means of a screw valve 33. Fastened to the outer wall of the diaphragm casing 17 is a set screw 34 aligned with. the connecting rod 21 so that their ends may abut. Confined bei t t th valve 19, the spring acting to force the sleeve against the pin 29, the latter against the sleeve 26 and the end of the connecting rod against the adjusting screw 34. The amount, of opening at the valve 19 in this position will of course depend upon the adjustment of the screw 34 which may be turned to project a greater or less distance into the valve casing to increase or decrease the normal sli ht opening of the valve in accordance with the partial or frac tional air flow desired through the line.

Before proceeding with a description of the operation of the device, it is pointed out that the inner side of the diaphragm 28 is in direct communication with the lower portion of the suction tube 13. The outer side of this diaphragm 28.and the inner side of the diaphragm 25, or in other words, the air space enclosed between the two diaphragms, is in communication with the upper portion of the suction tube. The outer side of the dia hragm 25 is always in communication with the atmosphere.

Briefly, the operation is as follows: Under normal conditions when no carriers are in .the lines, the. lines are maintained in operating condition by a partial or fractiona l flow of air.through theline, determined by the amount of opening to which the valve 19 is set by the adjusting screw 34. Under these conditions the valve 19 and diaphragm 28 have a counter-balancing effect upon each'other. That is, if the diaphragm 28 were to be disregarded there would be adecidedly unbalanced pressure upon the valve 19 itself. For on the left hand side of it the pressure is substantially atmospheric, while on the right hand side the pressure, i. e., the vacuum, is substantially equal to that of the suction producing device. This unbalanced pressure would tend to hold the valve closed, and, in the absence of the diaphragm 28, would have to be overcome before the valve could be opened. The diaphragm 28 is subjected to the same unbalanced pressure as the valve 19, but 1n the opposite direction. That is, the left hand side-"6f the diaphragm 28' is normally subjected to substantially the same pressure .as the right hand side of the valve 19, and

the right hand side of the diaphragm 28' to substantially the same pressure as the left hand side of the valve 19. In the particular embodiment here shown the diaphragm 28 has a slightly larger area than the valve 19, so that the net result of the unbalanced pressures upon the valve and diaphragm is.

a slight tendency to open the valve'a tendency which is overcome by the slightjpressure exerted by the spring 35.

As I have said, under normal conditions a "minimum flow of air is maintained through the cracked valve 19. When. a

carrier is inserted in the bell-mouth it acts as a plug, cutting ofi communicatien to the 25 and is sufficient to permit the atmospheric pressure upon the right of thislatter diaphragm to move it to the left, and

with it thevalve 19, thus opening the valve.

Were it not for the presence ofthe counter-balancing diaphragm 28, a much greater pressure reductionv in the chamber 17 would be required for opening the valve. This, in turn, would require a much more substantial minimum flow at all times when no carrier was being transmitted, and there-' fore a much greater expenditure of power. It would also involve lesssensitivepperation, Thus the presence of the diaphragm 28 not only provides better and more sensitive operation, but provides it at less cost. If now the carrier, during its flight through the line, races, or attains an excessive speed along, say, a descending grade of tube, the piston action of the carrier, acting upon the column of air between it and the suction drum, produces an increase in the rate of flow of this air column as well as the pres-- sure, and this increase in pressure occurs also in the chamber or space 17*. While this increase of pressure may be very slight, it will, with the aid of the unbalanced pressure of the spring 35,-be sutficient to move the diaphragm 25 outwardly, and the valve inwardly toward its seat, continuing until .the end of the connecting rod 21 abuts against the adjusting screw 34 to bring the valve to its normally open position of adjustment if the speed of the carrier, and hence the increase of pressure produced thereby, is suflicient. I

It should be observed further that when the valve 19 is in the full open position with a carrier in transit, and the speed of the carrier becomes excessive, producing an increase in pressure in the lower part of the line and the chamber 17, which actuates the diaphragms to move the valve 19 toward its seat, the increased flow of air under these conditions acting upon the valve 19 also assists the unbalanced pressure of the spring 35 and the diaphragm25 to move the valve to its normally slightly open position.

It will thus be seen that-the device, while serving to control the flow of air through a tube line when unoccupied, and also to regulate the flow of air with carriers in transit, is

of unusually simple construction involving few parts which, in their operatlon, are sub? ijected to little or no wear requiring repairs and replacements. Besides, the valve is one of great sensitiveness, capable of being adjusted so as to closely control the speed of carriers in a tube line in accordance with the conditions of travel and the requirements for their propulsion without the use of auxiliary mechanisms or timing devices.

I claim: I

1. In a pneumatic dispatch system, a tube line, a valve in the tube line controlling the flow of air therethrough, means for exerting a force tending to seat the valve, a device responsive to the pressure in the line for exerting an opposite force normally tending to balance the valve, a device for preventing the complete closing of the valve thereby to normally permit a partial flow of air through the line, and means cooperating with said device and responsive to variations in the pressure in the line for actuating the valve, substantially as described.

2. In a pneumatic dispatch system, a tube line, a normally open valve in the tube line controlling the flow of air therethrough, means for exerting a force tending to maintain the valve in its normally open position, a device responsive to the variations in ressure in the line for exerting an opposite orce substantially balancing the valve, and means vassociated with said'pressure responsive device which is actuated by a decrease in pressure in the line to increase the openin of the valve beyond the normal amount, and by an increase of pressure in the line to close the valve, substantially as described.

3. In a pneumatic dispatch system, a tube line, a normally open valve in the tube line controlling the flow of air therethrough, means for exerting a force tending to maintain the valve in its normally open position whereby to permit a partial flow of air through the line, a device responsive to variations in pressure in the line for exerting a force opposed to said first mentioned force tending normally to balance the valve, and a device which is caused to be actuated by va riations in pressure in the line and by atmospheric pressure to increase the valve opening beyond the normal amount when a carrier is inserted in the line, and to close the valve when the speed of the carrier be-.

comes excessive, substantially as described.

4. In a pneumatic dispatch system, a tube line, avalve in the tube line controlling the fiowoihair therethrough, means for exerting a force tending to seat the valve, a device responsive to variations in pressure in the line for exerting an opposite force substantially balancing the valve, an adjustable device for preventing the complete closing of the valve whereby to normally permit a partial flow of air through the line, and a diaphragm cooperating with said device which is responsive to. a decrease in static pressure in t e line "to open the valve and to an increase in static pressure in the line to close the valve, substantially as described.

5. In a pneumatic dispatch system, a tube line, a valve in the tube line controlling the flow of air therethrough, means for exerting a force tending to seat the valve, a diaphragm in communication with the suction. tube for exerting an opposite force tending to balance the valve, an adjustable device for preventing the complete closing of the valve whereby to normally permit a partial flow of air through the line, and a diaphragm which is in communication with the suction tube for actuating the valve in accordance with the pressure in the line, substantially as described 6. In a pneumatic dispatch system, a tube line including a suction tube, a valve in the suction tube which is normally open to per mit a partial How of air therethrough, a spring for exerting a force tending to seat the valve, 2. device for preventing the complete closing of the valve, a diaphragm responsive to the suction in the suction tube for exerting a force substantially balancing the valve, and a diaphragm associated with said first mentioned diaphragm which is in communication both with the suction tube and the atmosphere, substantially as described.

7. In a pneumatic dispatch system, a tube line including a suction tube, a valve in the suction tube, means acting normally to prevent seating of the valve thereby normally permitting a partial flow of air through the line, a spring tending to seat the valve, a diaphragm operatively connected to the walve which is responsive to the suction in the line to exert a force substantially balancing the valve, and a second diaphragm likewise operatively connected to the valve but independently of the first diaphragm which is responsive both to variations in pressure in the line and to atmospheric pressure to actuate the valve, in cooperation with the first mentioned diaphragm, to increase the amount of its opening when a carrier is inserted in the line, and to decrease the opening when the speed of a carrier becomes excessive, substantially as-described.

8. In a pneumatic dispatch system, a tube line, a valve in the tube line, means for exerting a force tendin to move the valve in one direction, and evices for exerting a force tending'to move the valve in the opposite direction, said devices including a pair of diaphragms o eratively connected to the valve, one of sai diaphragms being in communication on both sides with the source of power creating aiiow of air through the line,

suction tube, means associated with the valve for exerting a force tending to move the Valve in one direction, and devices associated with the valve tending to move it in the opposite direction, said devices including a pair of diaphragms operatively connected to the valve, but independently one of the other, one of the diaphragms being in communication on both sides with the suction tube, and the other in comfmunication on one of its sides with the atmosphere, substantially as and for the purposes described.

10. In a pneumatic dispatch system, a tube line including a suction tube, a spring actuated valve in the suction tube, and a pair of diaphragms operatively connected to the valve, one of the diaphragms being in communication on both sides with the suction tube, and the other in communication on one of its sides with the atmosphere, substantially as and for'the purposes described.

11. In a. pneumatic dispatch system, a

' tube line including a suction tube, a spring actuated valve in the suction tube line, a diaphragm in direct communication with the suction tube on one of its sides, and a second diaphragm, said diaphragms being operatively connected to the valve and enclosing between them an area in communicat-ion with the suction tube, substantially as and forthe purposes described.v

12. In a pneumatic dispatch system, a tube line including a suction'tube, a sprin actuated valve in the suction tube, a diap ragm in direct communication with the suction tube on one of its sides, and a second diaphragm, said diaphragms being operatively connected to the valve but independently of each other, and enclosing between them an area in communication with the suction tube, substantially as and for the purposes described.

13. In a pneumatic dispatch system, atube line, a springactuated valve in the line, a diaphragm in direct communication on one of its sides with the tube line, and a second diaphragm, said diaphragms being operatively connected to the valve and enclosing an air chamber communicating with the tube line, and said second diaphragm being exposed to the atmosphere on its outer side, substantially as and for the purposes described.

I 14. In a pneumatic dispatch system, a tube line,-a spring actuated valve in the line, means for holding the valve normally open to permit a partial flow of ..air through the line, a diaphragm in direct communication on one of its sides with the tube line, and a second diaphragm, saiddiaphragms being operatively connected, but independently of each other, to the valve, and enclosing an air chamber communicating with the tube line, and said second diaphragm being exposed to the atmosphere on'its outer side, substantially as and for the purposes described. v 1

In testimony whereof I aflix my signature.

' JOSEPH JOHN STOETZEL. 

